1. Field of the Invention
The invention relates to vehicle headlamps and is directed more directly to a reflector for such headlamps.
2. Description of the Prior Art
Headlamps for vehicles are commonly constructed such that a light source is positioned at the focal point of a parabolic reflector. In theory, this should produce a beam comprising a bundle of parallel rays pointed forwardly of the vehicle, with a concentrated "hot spot" in the axial center of the beam. In practice, the rays do not conform to the theoretical model. The light source is not a point source, producing diffusion of rays or "stray" light. Stray light above the horizontal is lost uselessly and is offensive and/or blinding to oncoming drivers. The immediate areas in front of the vehicle and to either side of the vehicle typically are under lit. Repointing the beam downwardly merely reduces the beam reach. There is a need for a reflector that spreads the beam horizontally from the axial hot spot.
Vehicle styling with aerodynamic shaping has limited the outer shell of the headlamp to a generally elongated, relatively narrow, rectangle. Large portions of the upper and lower surfaces of the parabolic reflector have been sacrificed to styling. Accordingly, the remaining portions must be shaped so as to efficiently project the available light to those parts of the road helpful to the driver, and not to areas that blind oncoming drivers and pedestrians. There is thus a need for a reflector which spreads the beam appropriately and which conforms to aerodynamic styling.
In an attempt to provide a reflector which solves the above described problems, reflectors have been provided which comprise a multitude of reflective panels joined together in a generally parabolic surface. Typically, the configuration of each panel is computer generated to provide light rays to a desired portion of the road. In manufacture of reflectors, after the panels are joined together, the reflective surface is coated with a material and, thereafter, aluminized. The coating, at and immediately after the time of application, tends to accumulate in the seams, or junctures, of the panels, usually running down a vertical seam until encountering a horizontal seam, at which point the coating material collects and hardens, forming irregularities in the surface of the reflector. Such irregularities can produce glare zones in the light pattern. Accordingly, there is a need for a reflector, as discussed above, and further having sections joined together in such a manner as to avoid formation of irregular beam patterns and consequent glare zones.
As headlamps have become smaller and the reflectors therein smaller, in response to styling mandates, it has become necessary to provide more intense light sources, such as High Density Discharge (HID) light sources. The result has been that a relatively small reflector surface is responsible for lighting a particular region. When a human eye in that region views the headlamp, the eye sees an intense light from the small region and experiences the light as brilliant and often blinding. When the same amount of light is received from a greater area, the eye is more tolerant. There is, therefore, a need for a vehicle headlamp reflector which casts a beam appropriately spread horizontally, which reflector is adapted to aerodynamic styling, avoids the formation of surface irregularities in its manufacture during the overcoating process, and which spreads the reflective surface as seen by the eye of an oncoming driver.
In U.S. Pat. No. 1,793,662, issued Feb. 24, 1931, in the name of W. H. Wood, there is disclosed a headlamp reflector having vertical bands through a portion of a metal reflector. The vertical bands appear to be formed in the reflector by vertical grooves in the metal.
U.S. Pat. No. 2,108,286, issued Feb. 15, 1938, in the name of C. E. Godley, shows a headlamp reflector with horizontal bands having different curvatures to spread and direct the light from the light source.
U.S. Pat. No. 3,511,983, issued May 12, 1970, in the name of W. H. Dorman, discloses a lighting device for dental and surgical procedures having a concave glass mirror surface with vertical rows or facets therein which are, alternatively, of convex or concave configuration. Between the rows are grooves, or, alternatively, ridges.